1. Field of the Invention
The present invention relates to a mobile terminal having a video call function, and more particularly to a method and device for setting an output volume of an audio signal to prevent acoustic shock in a mobile terminal.
2. Description of the Related Art
Generally, mobile terminals capable of sending or receiving images can offer video call services which send a user's image and display an image received from another user on a display screen. During a video call, the display screen is divided into a main screen and a sub screen to display two video images (one received and the other sent) simultaneously. Call participants can talk to each other, viewing the video images on the divided screen and hearing the voice outputted through the speaker.
Mobile terminals generally have a plurality of means for outputting sound sources, for example, a speaker for outputting sound sources such as a bell sound, MP3 music and an audio signal received during a video call, a receiver or a hands-free connector for outputting voice during a call, and an earphone connector for outputting voice or other sound sources during a call. Mobile terminals offering video call services have multiple sound data transmission paths corresponding to the respective sound source output means. Each of the sound data transmission paths may include a volume adjuster for setting an output volume of an audio signal. Mobile terminals output sound source data through a currently set transmission path at a volume level set by a volume adjuster of the current transmission path.
The sound data transmission path can be set according to the condition of connection between a mobile terminal and an external device or according to the kind of the sound source to be outputted. For example, when an earphone is connected to a mobile terminal through an earphone connector, a sound data transmission path corresponding to the earphone connector is set to output sound source data. When the mobile terminal offers video call services without being connected to any external device, a sound data transmission path corresponding to the speaker of the terminal is set to output sound source data received during the video call. In addition, a sound data transmission path corresponding to the receiver is set to output voice during a call. The volume level can be set through a key input according to the user's command.
Mobile terminals are becoming smaller, sleeker and lighter to meet the demands for improved design, portability and cost reduction. To comply with this trend, mobile terminals have been developed to allocate a speaker and a receiver to a single sound data transmission path and output sound source data through the single transmission path.
Conventional mobile terminals with separate a speaker and receiver output voice during a video call and voice during a general voice call through different transmission paths corresponding respectively to the speaker and the receiver at volume levels set by the volume adjusters of the respective transmission paths. However, mobile terminals with an integrated speaker and receiver output both of the above sound source data through a single sound data transmission path. Specifically, the integrated mobile terminals output voice during a video call in a default speaker mode and voice during a general call in a default receiver mode or normal mode.
Although the volume level can be set according to a sound output means or according to a call type such as a video call or a general voice call, the following problems may arise.
When a video call is initiated by an incoming call, an integrated mobile terminal sets a transmission path for outputting video call signals. A user can hear and talk to a partner through the speaker, while maintaining a distance from the mobile terminal to see the partner's image displayed on the display screen, with the volume being louder to accommodate the distance. However, the user may hold the mobile terminal close to ear to receive an incoming call, without knowing whether it is a video call or a general voice call. At this time, the user may be startled by the intense sound abruptly outputted at a high volume level which is set for a video call in the speaker mode.
Also, while making a voice call with the mobile terminal held close to the ear, the user may cause a sudden change to the speaker mode by an inadvertent pressing of a speaker mode key or the like. Then the user may experience a sudden acoustic shock due to the unexpectedly high-level of sound volume outputted through the speaker before moving the terminal away from the ear.